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MOLD. No. 561,554. Patented June 9, 1896.

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UNITED STATES I PATENT OFFICE.

JAMES D. BAKER, OF MONTREAL, CANADA, ASSIGNOR TO CHARLES FYFE, OF SAME PLACE, AND HENRY C. ROOME AND IVILLIAM G. ROOME, OF

JERSEY CITY, NEV JERSEY.

MOLD.

SPECIFICATION forming part of Letters Patent No. 561 ,554, dated June 9, 1896.

Application filed August 5, 1895.

molds for use in manufacturing plaster boards.

I will describe a mold embodying my inven-' tion, and then point out the novel features in the claims.

In the accompanying drawings, Figure 1 is a top view of a mold embodying my improvement. Fig. 2 is a bottom view of the same. Fig. 3 is a longitudinal section taken at the plane of the dotted line 3 3, Fig. 2. Fig. 4 is a transverse section taken at the plane of the dotted line at 4, Fig. 2. Fig. 5 is a transverse section of a plaster board produced in said mold, the plane of the section being indicated by the dotted line 5 5, Fig. 1. Fig. 6 is a top view of a mold of modified form- Fig. 7 is a transverse section of the mold illustrated in Fig. 6, this section being taken at the plane of the dotted line 7 7.

Similar letters of reference designate corresponding parts in all figures.

Referring, first, to the mold illustrated in Figs. 1, 2, 3, and 4, A A designate two parts of a mold, made of Wood or any other suitable material, each being made L-shaped, and the two being detachably connected in any suitable 1nanneras, for example, by means of hooks and eyes or pins C. The part A has a rabbet a along its two sides at the inner edge and in its upper surface, and the part A has a rabbet a along its two sides at the inner edge in its lower surface. By this eonstrue tion, when the mold is laid upon a suitable surface and filled with plaster, there will result a plaster board like that shown in Fig. 5.

In the rabbet a. of the part A a strip or strips of flexible material D will be inserted. Preferably I shall use burlaps for the said strip or strips. The said strip or strips will be laid so as to extend beyond the rabbet, in order that their edges may be incorporated in the plaster board formed in the mold. A

Serial No. 558.337. (N0 model.)

holding-piece E fits in the rabbet a above the flexible material, so as to retain the same in the mold during the molding and also preelude the plaster from covering the entire surface,the object being to provide the plaster board with a strip or strips of flexible material incorporated in it and projecting beyond it, so as to lap over and form a union with another plaster board.

It will be seen that the finished plaster board has a small rabbet at the edge or at the edges where the flexible material projects from it. The purpose of this rabbet is to prevent any crack from extending directly through the joint between two plaster boards. To produce this rabbet the holding-piece is made in transverse section a little wider than the rabbet a.

The advantage of making the mold in sections is to afford facility for disengaging it from the plaster board.

WVith the top of the mold as illustrated in Fig. 1, the smooth surface or finished coat of a plaster board made with such a coat would be at the top in molding. If desirable, a mold might be used inverted, or with what has been called the top, and as illustrated in Fig. 1 as the top laid downward, and if it were then laid upon a sheet of glass or something equally smooth, the finishing-eoat could be advantageously molded with a very smooth surface.

In Figs. 6 and 7 I have shown a rubber mold with glass laid in the bottom and with a single rabbet a extending all the way around. It is shown as having a glass plate F in the bottom of the molding-cavity, and is intended for molding the plaster board with the finished surface downward, or at the bottom of the mold. the rabbet will be made wider than the other two sides to produce a small rabbet in the plaster board adjacent to the projecting strip or strips of flexible material.

The strip or strips of flexible material will be laid upon the wider side of the rabbet a and a holding-piece E, made preferably of metal, so as to be heavy, will be laid upon the strip or strips of flexible material over the sides a of the said rabbet.

Preferably two sides a of As this mold may be readily bent to free the molded plaster board it need not be made in sections.

The glass plate is not an essential of the mold. Obviously the bottom of the mold might be provided with any surface Which I may desire to reproduce in the plaster board. It is, however, very advantageous, Where the plaster board is to form part of a ceiling or Wall having a finishing-coat, to mold upon glass, so as to produce such finishing-coatv The nails or upon the plaster board itself. other devices for securing plaster boards in position may then be driven through the rabbet of the board. after a number of plaster boards are put together Will cover the nails or other devices and also the flexible material.

Obviously the holding-piece E or E maybe made in sections.

hat I claim as my invention, and desire to secure by Letters Patent, is

1. A mold of angular form, having a rabbet extending on one side thoughout one portion of the edge of the molding-surface, and a rabbet on the other side, extending throughout another portion of the molding-surface, substantially as specified.

The filling of the rabbet' 2. A mold of angular form, made in two detachable sections and having a rabbet extending on one side throughout one portion of the edge of the molding-surface, and a rabbet on the other side, extending throughout another portion of the molding-surface, substantially as specified.

3. A mold of angular form, having a Slll" face capable of receiving a strip or strips of flexible material beyond the molding-cavity, and a holding-piece for retaining the said flexible material upon said surface, substantially as specified.

4. A mold of angular form having a rabbet capable of receiving a strip or strips of flexible material, and a holding-piece for retaining said flexible material in, the rabbet, and preventing that part in the rabbet from being covered by the moldedplaster, substantially as specified.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JAMES D. BAKER. Witnesses:

G. II. BARRON, C. CUSHING. 

